A thin-film transistor and a display panel are provided in which current characteristics of the thin-film transistor are improved by a dual gate electrode structure, and the output characteristics of the thin-film transistor are improved by dividing the top gate electrode (or bottom gate electrode) of the dual gate electrode into two electrodes and applying a back bias voltage to the top gate electrode adjacent to a source region. A high-resolution display panel or a transparent display panel is realized by increasing the aperture ratio (or transmittance) of the display panel using the highly integrated high-current device.